Currently, among the elderly people over 65 years old, the occurrence of aortic valve stenosis caused by aortic valve calcification is up to 2%-7%, and the proportion of aortic valve stenosis increases with age. Patients with serious aortic stenosis suffer from serious left ventricular dysfunction, which results in bad life quality of the patients and significant shortened lifetime. Effective treatments are required.
For patients with severe aortic valve in surgery indications, surgical prosthetic aortic valve replacement (either mechanical valve or biological valve) is still the preferred treatment, the aortic valve orifice area can often reach to larger than 1.5 cm2 after replacement. However, the incidence of deaths and other serious complications following surgical aortic valve replacement have been greatly increased in those patients who are elderly, with aortic stenosis at the final stage, or multiple systemic serious complications. Method of percutaneous balloon aortic valvuloplasty for the treatment of aortic stenosis in the elderly is no longer used for serious aortic stenosis due to high incidence of intraoperative and postoperative deaths, stroke, aortic rupture, serious aortic insufficiency and other serious complications, as well as occurrence of obvious stenosis of aortic valve in a short term (3-12 months) after the operation. In addition, it is very difficult in the clinical treatment for elderly patients with serious aortic stenosis but without surgical indications.
In the prior art, prior to the animal experiment, a pig or a sheep at a appropriate age is selected, surgical risk and match degree are evaluated after ultrasound examination and health observation by doctors, to determine the congruency of the diameter of the valve frame and the main pulmonary artery diameter, the size of the valve frame is required to match the caliber of the aorta or pulmonary artery to prevent paravalvular leakage or displacement and so on. Then animal clinical experiment is carried out according to animal clinical requirements, the treated biological valve is implanted into the body of the pig or the sheep, if the valve is observed by ultrasonography to work well upon feeding for an observation period of six months to one year, the biological valve is removed by anatomizing and the calcium content in biological valve tissue is detected by atom absorption spectroscopy to determine the anti-calcification properties of the biological valve.
There are some limitations to evaluate the biological valve calcification through animal clinical experiment, the high technical dependence on clinical surgeries and clinician's technique, the corresponding requirements to selection of animals, and other symptoms such as biological valve epidermidalization, growth of neoplasm etc. may occur due to long feeding period, feeding environment effects and individual differences, and cannot accurately and effectively reflect the chemical action of biological valve after chemical reaction with calcium ions. The existing methods not only increase the technical difficulty but also greatly increase the time and cost, meanwhile, the evaluation of the calcification performance of the biological valve is interfered by many factors.